The field of the present invention relates generally to air intake systems for an internal combustion engine.
Internal combustion engines produce mechanical power from the chemical energy contained in hydrocarbon fuel. The energy is released by burning or oxidizing the fuel internally within the engine""s structure (e.g., the cylinders of the engine). As such, the amount of energy or power released from the fuel is a function of the degree of oxidation and, therefore, is consequently dependent on the amount of oxygen available during combustion. It is presently understood that as a general principle the greater the degree of oxidation of the fuel the higher the efficiency (reflected for example in the gas mileage of an automobile) and the greater the power output (reflected for example in horsepower).
Combustion of hydrocarbon fuels in internal combustion engines has been found to produce generally three major pollutants: (1) oxides of nitrogen (NOx), (2) oxides of carbon (CO, CO2), and (3) hydrocarbons (HC). Carbon dioxide (CO2) is a generally considered a non-toxic necessary by-product of the hydrocarbon oxidation process. With respect to carbon monoxide (CO) and hydrocarbon emissions it is understood that increased oxidation during combustion tends to reduce the formation of these compounds by way of oxidation. With respect to NOx emissions, their formation is understood to be largely a function of combustion temperatures. However, it is also presently understood that leaner fuel-air mixtures and improved mixing of the fuel and air may tend to reduce NOx formation. In order to reduce the emissions from internal combustion engines directly to the environment, catalytic converters have been employed. Catalytic converters are costly and their effectiveness over time weakens requiring inspection and replacement to maintain performance. The life span of these devices, however, is understood to be a function of the amount of pollutants (primarily unburned hydrocarbons) that the device has processed. Accordingly, in addition to increasing the efficiency and power output of combustion, increased oxidation during combustion is also likely to increase the life span of the catalytic converter.
Reciprocating and rotary engines, such as the Wankel engine, comprise the two categories of positive displacement engines that are traditionally employed to power motor vehicles. In general a positive displacement internal combustion engine is an engine in which the flow of the fuel-air mixture is segmented into distinct volumes that are completely isolated by solid sealing elements throughout the engine cycle, creating compression and expansion through the physical volume changes within the chamber. Of the two engines, the reciprocating engine is by far the more common.
Reciprocating engines incorporate a piston that moves back and forth in a cylinder and transmits power through a connecting rod and crank mechanism to the drive shaft. A majority of reciprocating engines work on what is called a four-stroke cycle. That is, each cylinder of the engine requires four-strokes of its piston or two revolutions of the crankshaft to complete the sequence of events which produces one power stroke. The first stroke is termed an intake stroke. It starts with the piston at top center crank position and ends with the piston at the bottom center crank position. As the piston moves from the top to the bottom center crank position, fresh intake mixture generally comprised of air or air and fuel is drawn into the cylinder through an inlet valve, which typically opens just before the stroke starts and closes shortly after it ends. Whether the intake mixture drawn into the cylinder is comprised of air or air and fuel is dependent on the engine. For example, in a typical spark ignition engine, air passes through an air filter and then is mixed with fuel in the intake system prior to entry to the engine using a carburetor or fuel injection system. The air-fuel mixture is then drawn into the cylinder via the intake valve during the intake stroke. In comparison, a compression ignition engine inducts air alone into the cylinder during the intake stroke and the fuel is directly injected into the engine cylinderjust before combustion.
FIG. 6 is an illustration of a standard cylinder, piston and valve configuration for a reciprocating engine with the cylinder approaching bottom center crank position during an intake stroke. The inlet valve, through which the intake mixture is drawn, is generally comprised of an elongated rod called the valve stem and an integrally connected generally disc shaped surface called the valve head. The valve head is manufactured to have a seat that is adapted to mate with the internal edge surface of an orifice or port located usually in the top of the cylinder. The valve head and stem, even in the open position, constitute obstacles that may limit the flow of the intake mixture to the combustion chamber or cylinder. Furthermore, over time the surfaces of the head, stem and port are prone to accumulate particulate matter, which further tends to obstruct the flow of intake mixture into the cylinder.
In order to increase the volume of intake mixture into the combustion chamber, devices such as superchargers (which admit pre-compressed fresh mixture) and turbochargers (which admit fresh mixture compressed in a compressor driven by an exhaust turbine) have been employed. Unlike naturally aspirated engines (engines that admit atmospheric air), engines that employ these devices admit compressed intake mixtures into the combustion chamber to increase the quantity of intake air admitted into the combustion chamber during an intake stroke. From a functional standpoint, it is noted that superchargers typically increase the pressure of the intake mixture by a much greater amount than a turbocharger, and as such limitations by the intake valve to the flow of the intake mixture are less of an issue when a supercharger is employed. Turbochargers and superchargers, however, draw useable power from the engine, add noticeable weight to the motor vehicle, require additional space within the engine compartment for mounting, are expensive to manufacture, and employ moving mechanical elements that are prone to wear and, thereby, over time necessitate repair. Furthermore, these devices are difficult and costly to retrofit onto existing engines.
In light of the foregoing, it is desirable to provide an air intake device and method suitable for naturally aspirated and turbo-charged positive displacement internal combustion engines.
The present invention relates in one aspect to an air intake flow device capable of manipulating the airflow in an air entry chamber of a positive displacement internal combustion engine.
According to one aspect as described herein, the air intake flow device comprises a configurable skirt and a plurality of vanes extending from the configurable skirt, wherein the skirt is adaptable to a plurality of air entry chamber shapes.
According to another aspect, the air intake flow device comprises a skirt and a plurality of adaptable vanes extending from the skirt, wherein the vanes are capable of being oriented to manipulate impinging airflow into a plurality of configurations.
According to yet another aspect as described herein, the air intake flow device comprises a skirt defining an airflow passageway and a plurality of vanes extending at a first angle and a second angle from the skirt into the airflow passageway, wherein the first angle is between 25 and 35 degrees relative to an axis perpendicular to the airflow passageway.